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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have compared neuromuscular block in the rectus abdominis and the hand muscles in 11 adult patients. Atracurium 0.5 mg kg-1 was administered by single bolus and anaesthesia maintained with isoflurane and nitrous oxide in oxygen. Train-of-four (TOF) stimulation was applied to the 10th intercostal space in the anterior axillary line and to the ulnar nerve at the wrist. Electromyographic (EMG) responses were recorded over the rectus abdominis and hypothenar muscles. Neuromuscular block had a significantly faster onset in the rectus abdominis (mean 1.6 (SEM 0.2) min) than in the hand (2.4 (0.3) min) (P less than 0.001). Recovery occurred more rapidly in the rectus abdominis: time to 25% TOF recovery was 39 (3) min at rectus abdominis and 51 (4) min at the hand (P less than 0.001). Time to 75% TOF recovery was 56 (4) min at rectus abdominis and 72 (6) min at the hand (P less than 0.001).
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PMID:Comparison of atracurium-induced neuromuscular block in rectus abdominis and hand muscles of man. 138 22

The differences between neuromuscular blockade of the adductor muscles of the vocal cords and the adductor pollicis were examined in 20 adult women anesthetized with fentanyl and propofol. Vecuronium 0.04 or 0.07 mg/kg was given as a single bolus by random allocation. The force of contraction of the adductor pollicis was recorded. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Train-of-four stimulation was applied to the recurrent laryngeal nerve at the notch of the thyroid cartilage and to the ulnar nerve at the wrist. Neuromuscular blockade had a faster onset, was less intense, and recovered more rapidly at the vocal cords. With 0.04 mg/kg, maximum blockade of first twitch (T1) was 55 +/- 8 (mean +/- standard error of the mean [SEM]) and 88 +/- 4% at the vocal cords and the adductor pollicis, respectively (P = 0.006). Onset time was 3.3 +/- 0.1 and 5.7 +/- 0.2 min, respectively (P = 0.000001), and time to 90% T1 recovery was 11.3 +/- 1.6 and 26.1 +/- 1.8 min, respectively (P = 0.001). With 0.07 mg/kg, onset time was unchanged; maximum blockade was more intense, being 88 +/- 4 and 98 +/- 1%, respectively (P = 0.04 between muscles); and time to 90% T1 recovery was 23.3 +/- 1.8 min at the vocal cords versus 40.3 +/- 2.9 min at the adductor pollicis (P = 0.001). Approximately 1.73 times as much vecuronium was required at the larynx compared with the dose required at the adductor pollicis for the same intensity of blockade.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vecuronium neuromuscular blockade at the adductor muscles of the larynx and adductor pollicis. 1160 8

We were interested in determining the infusion rate of vecuronium required to maintain approximately 95% neuromuscular blockade in children during halothane-narcotic-nitrous oxide (0.8% end-tidal concentration), isoflurane-narcotic-nitrous oxide (1.0% end-tidal concentration), or narcotic-nitrous oxide anesthesia. Neuromuscular blockade was monitored by recording the electromyographic activity (Datex NMT) of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Effective vecuronium infusion requirements averaged 1.5 +/- 0.1 micrograms.kg-1.min-1 (mean +/- SEM) during isoflurane-narcotic-nitrous oxide anesthesia, 1.9 +/- 0.1 micrograms.kg-1.min-1 during halothane-narcotic-nitrous oxide anesthesia, and 2.4 +/- 0.3 micrograms.kg-1.min-1 during narcotic-nitrous oxide anesthesia. Infusion requirements significantly decreased after the first 30 min of infusion in the presence of both potent inhalation anesthetics, but did not change with time during narcotic-nitrous oxide anesthesia. There was no evidence of decreasing infusion requirements during prolonged vecuronium infusion (2.5 h). There was no difference in the rate of spontaneous or pharmacologically induced recovery between anesthetic groups. The mean recovery index (T25-75) after termination of the infusion was 13.7 min.
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PMID:Vecuronium infusion requirements in children during halothane-narcotic-nitrous oxide, isoflurane-narcotic-nitrous oxide, and narcotic-nitrous oxide anesthesia. 167 45

To determine the influence of sampling site on atracurium pharmacokinetic-pharmacodynamic relationships, blood was drawn simultaneously from the radial artery and peripheral vein during a 20-minute period after injection of atracurium, 0.2 mg/kg, in eight patients. Atracurium and laudanosine concentrations were measured by HPLC. Neuromuscular blockade was measured at the adductor pollicis, after stimulation of the ulnar nerve. Venous levels were lower than corresponding arterial values for up to 20 minutes, and this difference was marked for the early samples. Neuromuscular blockade was maximum after 5 to 7 minutes, much later than the peak venous concentration (1 to 3 minutes). Nonparametric analysis yielded (mean +/- SEM) a rate constant, concentration for 50% blockade, and slope of the effect-concentration relationship of 0.092 +/- 0.01 min-1, 379 +/- 27 ng/ml, and 7.3 +/- 1.67, respectively, when based on arterial samples. The values were statistically different (0.135 +/- 0.011 min-1, 235 +/- 42 ng/ml, and 3.41 +/- 0.37, respectively) when venous levels were used (p less than 0.05). It is concluded that forearm venous levels do not correspond to adductor pollicis neuromuscular blockade and the kinetics and kinetic-dynamic relationship for atracurium are heavily dependent on sampling site.
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PMID:Pharmacokinetics and pharmacodynamics of atracurium obtained with arterial and venous blood samples. 202 28

Suxamethonium increases neuromuscular block produced by non-depolarizing agents administered subsequently. To determine if this effect has a pharmacokinetic or pharmacodynamic origin, 18 ASA physical status I or II adults received atracurium 0.2 mg kg-1, with (n = 10) or without (n = 8) previous injection of suxamethonium 1 mg kg-1, during a thiopentone-nitrous oxide-isoflurane (0.5% end-tidal) anaesthetic. Arterial blood samples were obtained and plasma atracurium concentration measured by HPLC. Train-of-four stimulation was applied to the ulnar nerve and the force of contraction of the adductor pollicis muscle was recorded. Mean (SEM) volume of distribution was slightly greater with previous suxamethonium (143 (13) ml kg-1) than without (109 (5) ml kg-1) (P less than 0.04). Mean elimination half-life was unaffected (20.3 (0.8) min and 20.4 (1.6) min, respectively). Neuromuscular block was more intense and recovery was slower with previous administration of suxamethonium. Atracurium concentration at 50% block (Cpss50) was 305 (30) ng ml-1 with and 454 (25) ng ml-1 without previous suxamethonium (P less than 0.01). It is concluded that suxamethonium may be associated with a slight increase in the volume of distribution of atracurium, but this effect is more than compensated by a decrease in atracurium concentration required for a given effect.
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PMID:Pharmacokinetics and pharmacodynamics of atracurium with and without previous suxamethonium administration. 193 14

We were interested in determining the infusion rate of mivacurium required to maintain approximately 95% neuromuscular blockade during nitrous oxide-halothane (0.8% end-tidal) or nitrous oxide-narcotic anesthesia. Neuromuscular blockade was monitored by recording the electromyographic activity (Datex NMT) of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Mivacurium steady-state infusion requirements averaged 315 +/- 26 micrograms.m-2.min-1 during nitrous oxide-halothane anesthesia and 375 +/- 19 micrograms.m-2.min-1 (mean +/- SEM) during nitrous oxide-narcotic anesthesia. Higher levels of pseudocholinesterase activity were generally associated with a higher mivacurium infusion requirement. During both anesthetics, younger age was associated with a higher infusion requirement when the infusion requirement was calculated in terms of micrograms.kg-1.min-1. This difference was not present when the infusion rate was calculated in terms of micrograms.m-2.m-1. There was no evidence of cumulation during prolonged mivacurium infusion. There was no difference in the rates of spontaneous or reversal-mediated recovery between anesthetic groups. After the termination of the infusion, spontaneous recovery to T4/T1 greater than or equal to 0.75 occurred in 9.8 +/- 0.4 min, with a recovery index, T25-75, of 4.0 +/- 0.2 min (mean +/- SEM). In summary, pseudocholinesterase activity is the major factor influencing mivacurium infusion rate in children during nitrous oxide-narcotic or nitrous oxide-halothane (0.8% end-tidal) anesthesia.
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PMID:Mivacurium infusion requirements in pediatric surgical patients during nitrous oxide-halothane and during nitrous oxide-narcotic anesthesia. 214 69

Mivacurium chloride is a new, short-acting nondepolarizing neuromuscular blocking agent presently undergoing clinical evaluation. The neuromuscular effects of mivacurium and suxamethonium given by bolus and infusion were compared in adult patients during nitrous oxide-oxygen-opioid anaesthesia. Neuromuscular block was monitored by recording the compound electromyogram of the adductor pollicis muscle resulting from supramaximal train-of-four stimuli applied to the ulnar nerve. Time to onset of complete block and recovery to T5 were significantly shorter for suxamethonium than for mivacurium (1.0 (0.1) v. 2.5 (0.3) min and 6.4 (0.7) v. 17.5 (1.8) min; mean (SEM]. Conditions for tracheal intubation were similar in the two groups although intubation was performed 0.75-1.3 min later following mivacurium. The infusion rate required to maintain neuromuscular block was 88.6 (10.4) micrograms kg-1 min-1 for suxamethonium and 7.8 (1.2) micrograms kg-1 min-1 for mivacurium. There was a significant negative correlation between recovery to T5 and infusion rate for mivacurium and for suxamethonium. It was equally easy to titrate the infusion rate to the desired degree of block in each group. The recovery index (T25-T75) after the infusion stopped was similar in patients who received mivacurium and those who received suxamethonium.
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PMID:Comparison of mivacurium and suxamethonium administered by bolus and infusion. 252 44

Mivacurium is a new short-acting competitive neuromuscular blocking agent. Infusion requirements for the maintenance of a stable 90-99% muscle twitch depression were determined in 28 children anaesthetized with nitrous oxide and 1% halothane (inspired) in oxygen or nitrous oxide in oxygen and opioid. Neuromuscular block was assessed by monitoring the force of contraction of the adductor of the thumb during train-of-four (TOF) stimulation at 0.1 Hz. Infusion rate and twitch depression were analysed from 15 to 75 min and from 75 to 135 min after the start of the infusion. In the first period of evaluation, the mean infusion requirement was 10.4 (SEM 0.92) micrograms kg-1 min-1 during the halothane anaesthesia and 13 (1.4) micrograms kg-1 min-1 during the opiod anaesthesia (P less than 0.05). This difference was present also during the second 60-min period. There was no significant correlation between infusion rates required to maintain greater than 90% depression of the first twitch (T1) of the TOF and plasma cholinesterase concentrations. Regardless of the anaesthetic regimen, children recovered rapidly after discontinuing the infusion. The recovery index (25-75% recovery of T1) for all patients was 5.4 (0.57) min with no significant differences between the groups.
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PMID:Continuous infusion of mivacurium in children. 253 33

Vecuronium (V) and atracurium (A) were compared in a randomised study in premedicated patients undergoing laparoscopy for gynecological pathology. Both groups contained ten patients. Anesthesia was induced with fentanyl (0.1 mg) and thiopentone (1 mg/kg initially and subsequently 4 mg/kg). A priming dose of vecuronium (20 micrograms/kg) or atracurium (100 micrograms/kg) was given one minute before the intubating dose (60 micrograms/kg for vecuronium and 300 micrograms/kg for atracurium). Ninety seconds thereafter intubation was performed. Maintenance of anesthesia consisted of isoflurane at an inspiratory concentration of 1% in a mixture of O2/N2O (50%/50%) with small supplements of fentanyl. Neuromuscular block was monitored with the Datex Relaxograph. Results show that neither drug offers major clinical advantages over the other: there is no difference in speed of onset (V:T190sec 14.6 +/- 4.3%; A:T190sec 23.5 +/- 6.5%; Mean +/- SEM) and duration of neuromuscular block (V:T150sec 34.2 +/- 3.5 min; A:T150sec 41.3 +/- 2.8 min; Mean +/- SEM) and intubation conditions are almost identical.
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PMID:Priming with vecuronium and atracurium--a comparison. 288 97

We were interested in determining the dose-response relationship of atracurium in children (2-10 yr) during nitrous oxide-isoflurane anesthesia (1%) and the atracurium infusion rate required to maintain about 95% neuromuscular blockade during nitrous oxide-halothane (0.8%), nitrous oxide-isoflurane (1%), or nitrous oxide-narcotic anesthesia. Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle resulting from supramaximal stimulation at the ulnar nerve at 2 Hz for 2 sec at 10-sec intervals. To estimate dose-response relationships, three groups of five children received 80, 100, 150 micrograms/kg atracurium, respectively. During isoflurane anesthesia, the neuromuscular block produced by 80 micrograms/kg was 23.6% +/- 6.5 (mean +/- SEM), by 100 micrograms/kg was 45% +/- 7.2, and by 150 micrograms/kg was 64% +/- 8.7. The ED50 and ED95 (estimated from linear regression plots of log dose vs probit of effect) were 120 micrograms/kg and 280 micrograms/kg, respectively. At equipotent concentrations, halothane and isoflurane augment atracurium neuromuscular block to the same extent, compared to narcotic anesthesia. Atracurium steady-state infusion requirements averaged 6.3 +/- 0.6 micrograms . kg-1 . min-1 during halothane or isoflurane anesthesia; the requirements during balanced anesthesia were 9.3 +/- 0.8 micrograms . kg-1 . min-1 (P less than 0.05). There was no evidence of cumulation during prolonged atracurium infusion.
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PMID:Atracurium infusion requirements in children during halothane, isoflurane, and narcotic anesthesia. 315 54


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